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Beza gambar guna SLR telephoto 200mm dgn telescope 1250mm 5 Disember 2009

Posted by azmirul in Astronomy, Photography.
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Kalo nak tahu beza result guna lens magnification/zoom yg berbeza, bleh tgk comparison gambar kat bawah (camera SLR tu abang aku punya, telescope tu guna aku punya Orion Maksutov-Cassegrain Apex 90mm):

Magnification=Focal length of the Objective/Focal length of the Eyepiece

kalo ikut formula kat atas dgn “andaian”[1] focal length eyepiece utk SLR adalah 50mm, telephoto lens 200mm* bersamaan dgn magnification sebanyak 320/50=6.4x dan gambar no dua guna 1250mm focal length telescope adalah 1250/50 = 25x

*35mm equivalent focal length adalah 320mm

update (8 Dec 2009):
utk makluman jarak antara cell tower dgn telescope dlm 0.52 km

1. Canon EOS 350D + 200mm telephoto lens (4x 6.4x magnification)

2. Canon EOSD 350 + telescope Apex1250mm (25x magnification)

3. Gambar cell tower yg sama without any zoom magnification guna iphone utk comparison

(sorry gambo gelap, masa captured berbeza dgn gambar1 dan 2 iaitu waktu petang semalam, gambo ni aku baru capture jam 7 lebih pagi tadi sebab tak sabo2 nak submit kat blog ni heher)

p/s: lepas ni, nak try ambil gambar guna telescope baru aku tu guna magnification eyepiece yg lagi power (>50x)

[1] ref:

http://photography-on-the.net/forum/showthread.php?t=29133
http://www.photography-forums.com/calculate-zoom-t4135.html
http://photography-on-the.net/forum/showthread.php?t=21278

Telescope baru aku 5 Disember 2009

Posted by azmirul in Astronomy.
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ni gadget terbaru aku:  Orion Apex 90mm Maksutov-Cassegrain

aku punya add-on Accessories:

2x barlow lens, zoom eyepiece 7-21mm (60x – 178x), EOS slr ring adapter,  webcam adapter

Specifications
Optical design: Maksutov-Cassegrain
Aperture: 90mm
Effective focal length: 1250mm
Focal ratio: f/13.9
Central obstruction diameter: 29mm
Primary mirror coating: Aluminum with overcoat
Meniscus lens coating: Anti-reflection multi-coatings on both sides of lens
Eyepiece adapter: Accepts 1.25″ format accessories, camera t-threads
Eyepiece: 25mm Sirius Plossi, fully coated with multi coatings, 1.25″ format
Magnification with supplied eyepiece: 50x
Actual field of view with supplied eyepiece: 0.96degree
Diagonal: 45 degree correct-image diagonal, 1.25″ format
Near focus (with supplied eyepiece and diagonal): Approximately 13.5 feet
Finder scope: 6x magnification, 20mm aperture, correct-image, achromatic, 6.2 degree field
Optical tube mounting block: Fits standard photo-style tripods
Case: Deluxe carry case for optical tube included
Weight: 3.7 lbs (2.1 kg)
Length: 1-.5″ (without eyepiece or diagonal attached)